css - Adding overlay over google maps, leaves bottom part of map showing -

i trying use google maps location background page. however, overlay not cover entire map, bottom of map showing.

even when try set height of map-canvas , overlay 100vh map still exceeds overlay.

function initialize() {    var mapoptions = {      zoom: 15,      center: new google.maps.latlng(0, 0)    };      var map = new google.maps.map(document.getelementbyid('map-canvas'), mapoptions);  }    function loadscript() {    var script = document.createelement('script');    script.type = 'text/javascript';    script.src = 'https://maps.googleapis.com/maps/api/js?v=3.exp' + '&signed_in=true&callback=initialize';    document.body.appendchild(script);  }    window.onload = loadscript;

html, body {    height: 100%;  }  #map-canvas {    height: 100%;    width: 100%;    z-index: 0;  }  .overlay {    height: 100%;    width: 100%;    position: absolute;    top: 0;    left: 0;    background: rgba(0,0,0,0.5);    z-index: 1;  }

<script type="text/javascript"        src="https://maps.googleapis.com/maps/api/js?key=aizasyd1izgpwuoiz6hxudt6hscusa0oaxdggj4">  </script>    <div id="map-canvas"></div>  <div class="overlay"></div>

the #map-canvas have different position .overlay, because it's position affected padding/margin of page.

you have these options(there may more):

1. remove padding/margin:

   html, body {  height: 100%;  margin:0;  padding:0; } 

2. when want preserve padding/margin , want overlay cover map regardless of map-size/position, use .overlay child of #map-canvas :

    <div id="map-canvas"><div class="overlay"></div></div> 

   to make work must set noclear-option of map true (otherwise api remove .overlay)

function initialize() {    var mapoptions = {      zoom: 15,      noclear: true,      center: new google.maps.latlng(0, 0)    };      var map = new google.maps.map(document.getelementbyid('map-canvas'), mapoptions);  }    function loadscript() {    var script = document.createelement('script');    script.type = 'text/javascript';    script.src = 'https://maps.googleapis.com/maps/api/js?v=3.exp' + '&signed_in=true&callback=initialize';    document.body.appendchild(script);  }    window.onload = loadscript;

html,  body {    height: 100%;  }  #map-canvas {    height: 80%;    width: 70%;    z-index: 0;  }  .overlay {    height: 100%;    width: 100%;    position: absolute;    top: 0;    left: 0;    background: rgba(0, 0, 0, 0.5);    z-index: 1;  }

<div id="map-canvas">    <div class="overlay"></div>  </div>